Never Trust A Guy Named Bill
by Burning Underground
Summary: *Weirdmageddon never happened* The twins go back to Piedmont, California, but a demon follows them there. What happens? Billdip
1. Chapter 1

**This is my first Gravity Falls fanfiction, so I hope you all enjoy it!**

 **I don't own anyone.**

 **[~~~~~~~~~~~~~~~~~~~~]**

The pine trees in Gravity Falls swayed gently, the area seeming calm and serene. Nobody would know of what hid in this town, or of the amazing summer that two kids had.

Dipper Pines sat beside a river in the forest, remembering everything that has happened to him and his twin sister, Mabel, all summer. Gravity Falls was strange, and the twins hadn't even been able to scratch the surface of what lives in the town. Of course, summer always had to come to an end, and that brought pure sadness out of Dipper. He wanted to stay, but he had school, and he wasn't about to leave Mabel.

Dipper sighed as he stood up. Today was the day that they would leave for Piedmont, leaving Gravity Falls until, hopefully, they would be able to come back next summer. Dipper slowly made his way back to the Mystery Shack, dread rising with each step.

Mabel stood in front of the Mystery Shack, waiting for her brother so they could say their last goodbyes. Overall, the summer was fun: she made new friends, got a pig, fell in love with a lot of boys, only to be let down, and fought a lot of paranormal beings with her brother. Sure, the boy thing sucked, but the rest of the summer made up for that.

She started tapping her foot impatiently, never being the type of girl to just stand around. Where was Dipper? He said he'd be back soon, but he's been taking an hour!

Finally, she saw her brother come out of the thick shrubbery in the forest, a sad frown on his face. She knew that he didn't want to go, she honestly didn't either, but she was definitely more excited to start school.

She ran up and quickly hugged her brother. "Dipper! Where were you! I've been waiting for a whole hour!"

"It's only been 20 minutes, Mabel." Dipper replied, though he wished it was longer.

The mystery twins walked towards their Grunkle Stan's 'House of Mystery.' Their steps seemed to slow, knowing who all was waiting inside. All of their friends and family were gathered up, ready to say goodbye. They took a deep breath when they got to the door and opened it.

A bunch of sad faces turned happy at the sight of the two walking in. They could see through the happy masks though, and it just made them even sadder. Grenda and Candy ran quickly to Mabel and hugged her tightly.

"We are going to miss you, Mabel." Candy said, her voice cracking as if she was about to cry.

"Make sure you call us!" Grenda said, her voice just as sad, but still loud.

Mabel smiled and hugged her best friends tightly. "I'll miss you too! But don't worry, I'll call you everyday!"

Dipper looked at his sister with a small smile before they both were scooped up into Soos' arms. "I'm gonna miss you dudes."

The twins smiled and hugged him back, tears brimming their eyes. "We're gonna miss you too, Soos."

When he let the two go, Dipper looked at his crush, Wendy. The now thirteen year old boy let out a quiet sigh before walking over to her.

"Uh... H-Hey Wendy..." Dipper smiled nervously.

Wendy looked down and smiled. "Hey, Dipper. It kinda sucks that you and your sister are leaving. I've got to say, this was the best summer I've ever had."

"R-Really?" Dipper blushed, a wide smile on his face.

"Yeah, you two have really opened my eyes to the other, paranormal, side of this town. But don't worry, I'll wait until next summer so you won't be left out."

"Heh..." Dipper blushed more as he chuckled nervously.

"I'll see you later, dude." Wendy smiled before walking off to get a Pitt cola.

"Bye Wendy!" Dipper called out, proud that he didn't stutter.

Mabel looked at Dipper with a small smile before they both walked towards there Grunkle Stan and Great Uncle Ford. They found themselves wrapped up in Stan's arms, the old man holding them in a tight hug. They smiled and hugged him back just as tight.

"You behave around your parents, okay? I don't want them calling me about some crazy thing you learned from me."

The two nodded and Mabel 'zipped' her lips shut to show she wouldn't tell.

Dipper looked at Ford. "Are you sure that Gravity Falls will be safe? Bill is still out there..."

"We'll all be fine, Dipper. Just go to school."

Out of all of the paranormal beings they have met, Bill Cipher is the most dangerous. The yellow triangle has been the twins' enemy since they first met, and he even possessed Dipper's body! They figure that he's hiding somewhere right now, planning the domination of their world.

Yes, Bill was actually hiding, but at the moment he was watching the twins. He figured out that they were leaving, but he didn't know why, until he heard one of their friends say that they're going to their original home in Piedmont, California. For some reason, that made Bill sad. Perhaps it was because he was losing his favorite puppet, Dipper. He has been intrigued with him ever since he and his sister defeated him the first time.

He watched as six fingers gave the kid one of his journals, to keep it safe. That left the triangle wondering.

 _'Maybe, if I follow them, then I can get both the journal and pine tree...'_

As the Pines twins stepped into a bus, the triangle demon laid out his plan. And with that, he flew to a nearby bus stop.

Dipper sighed as he stared out of the window. Mabel sat beside him, cuddling her pig, Waddles. He felt... unfinished, leaving Gravity Falls. Maybe it was because Bill was still out there...

Suddenly the bus stopped, and a boy about their age walked on. His hair was a short, golden blonde color and his eyes shone blue. His teeth were set in a grin. He wore a yellow sweater with a black bow tie and jeans. The guy seemed... unsettling to Dipper, but to Mabel... Well...

"Ooh lala" Mabel's smile was wide as she stared at the person.

Dipper rolled his eyes. The person looked at them and grinned, sitting in the seat across from them.

"Hi! I'm Mabel! And this is Waddles!" Mabel smiled holding up her pig proudly.

"Nice pig. I'm Bill." The boy grinned, his arms crossed.

Mabel squealed, holding Waddles close. Dipper's eyes widened as he looked at the boy. "Did you just say Bill!?"

"Yeah, do you have a problem with my name, boy?" Bill said, his grin never leaving.

"Yes, actually, I do." Dipper crossed his arms.

"Sorry about Dipper, he doesn't really like that name because of someone he met before." Mabel said.

"I don't trust people with the name Bill." Dipper crossed his arms.

Bill laughed. "That's funny. Us Bills are naturally trustworthy."

Mabel giggled. "You're funny." Then she whispered, "And handsome..."

Bill just laughed. "So, where are you two heading?"

"Piedmont, California." Mabel answered with a bright smile.

"Really? That's where I'm going! My parents sent me here for the summer, and now I'm going back home." Bill smiled.

"Really!?" Mabel shouted. "That's what happened to us! We're so much alike!"

Suddenly, Mabel and Bill were engrossed in a conversation while Dipper looked out of the window.

They stayed like that the whole trip.


	2. Chapter 2

**By the by, this takes place after 'The Last Mabelcorn'**

 **[-]**

The bus came to a screeching stop, and the three stepped out. Mabel giggled as she said goodbye to Bill. Bill smiled then looked at Dipper, his blue eyes seeming to search for something. It only lasted for a second though before a grin spread on his lips.

"I hope we can be good friends, Pi- Dipper." Bill internally winced at having to call Dipper by his name rather than 'pine tree.'

Dipper caught the slip up and stared at Bill with interrogating eyes, looking for any hint that this could be Bill Cipher.

It seemed that Bill was good at hiding though, so Dipper gave up... for now...

Mabel dreamily waved at her new crush as he walked off. Dipper rolled his eyes. "Mabel, are you seriously going to trust him?"

"Why wouldn't I? That triangle guy can't turn into a human... right?" The young girl shook her doubt away. "Besides, why would Bill want to follow us here, anyway?"

Dipper sighed. "I don't know. Bill could want the journal..."

"Or you."

"What? Why me?"

"I've noticed that he likes to mess with you a lot... He might even want you for some evil plot or something..."

Dipper shook his head. "He's already possessed me to get rid of the laptop. Why would he want me now?"

Mabel shrugged. "This is just further proof that he didn't follow us here, and that was just some ordinary, dreamy guy named Bill. I mean, Bill is a really common name."

Dipper sighed. "I guess you could be right... but I'm still not trusting him until I know for certain."

"Alright, bro bro, whatever you say. Let's go home now."

Dipper nodded and grabbed his luggage, walking towards their house with his sister beside him.

Meanwhile, Bill Cipher was walking down the street, a huge grin on his face. He chuckled as he saw business men and women walking home from work, a truly miserable look on their faces. He closed his eyes as he whistled a happy toon. He was going to get that journal, and while he was at it, take Dipper away.

He stopped to sit on a bench and examined his new body. He hated being a human, but for right now he had to deal with it. He traced one vain on his pale skin with a small chuckle, gently pressing down on the vain that was sticking out. He could feel the blood coursing though those blue lines, and he loved the feeling of it. Bill leaned back in the bench with a smirk.

 _'Once I get that journal and Pine tree, I'll finally take over this stupid dimension.'_

 **[-]**

The mystery twins laid eyes upon their home. The lawn was freshly cut and the white paint looked clean. Their mother was a neat freak, so they didn't really pay any mind to it. The door opened before the two even reached the porch, revealing their parents.

"Mom! Dad!" The two shouted as they dropped their luggage and raced towards their parents, who scooped them up into their arms. The four stayed in a tight group hug for a couple of minutes before they let go.

"So, how was it?" Their mom asked.

"It was amazing!" Mabel shouted excitedly.

Dipper nodded in agreement. "Will we be able to go back next summer?"

Their parents looked at each other before nodding. "I don't see why not."

Dipper and Mabel smiled widely before Mabel ran back to their luggage, grabbing Waddles and bringing him back to their parents. "Say hi to Waddles!"

Their mother giggled. "Now, remember what we said about him. You can keep him as long as he doesn't make any messes."

"I promise that won't happen, right Waddles!?" Mabel hugged her pig as he let out a cute little oink.

Mrs. Pines smiled. "Good. Now, you two must be tired and hungry from your trip. I made a meal for you both, so go eat and unpack before you go to sleep. You do start school tomorrow."

The twins nodded before grabbing their luggage and walking in. They walked up to their room, that they shared, and set their luggage on their beds before running downstairs to eat.

The Pines family had fun as they ate. Mabel was talking about the non-paranormal stuff that happened on their trip, like fishing and winning Waddles. They decided to keep the true Gravity Falls a secret, not wanting to jeopardize their chances of going back.

After they ate, the twins got ready for bed, already thinking about what may happen on their first day of school.

"Do you think Bill will be there?" Mabel asked with dreamy eyes.

"Mabel, remember what happened the last couple times you've 'fallen in love' with someone? Gabe, Gideon-"

"Yeah, yeah. I know, but this feels different. I know he's not going to turn into some gnomes or become psychopathic. This feels real."

Dipper just rolled his eyes and laid back in his bed. "Whatever you say, Mabel..."

With that, the two fell asleep with a dream demon hanging over their heads, a grin on his now human face...


End file.
